Spiral counterbalance unit



Dec. 3, 1968 D. H. ROWE ET AL I SPIRAL COUNTERBALANCE UNIT Filed July 30, 1965 United States Patent 3,413,680 SPiRAlL COUNTERBALANCE UNIT Dale H. Rowe and Roy Ralph Jackwig, Galesburg, 111., assignors to Rowe Manufacturing Company, Galesburg, Iil., a corporation of Illinois Filed July 30, 1965, Ser. No. 476,009 6 Claims. (Cl. 16198) ABSTRACT UP THE DISCLOSURE There is disclosed a counterbalancing spring unit for overhead garage doors comprising a bracket, a shaft fixed with respect to the bracket, a rotatable drum on the shaft and a spiral spring having an inner end fixed with respect to the shaft and an outer end connected to and rotatably biasing the drum. A cable is wound on the drum and has its outer end detachably connected to the bracket for maintaining the spiral spring in a pretensioned condition prior to installation of the unit.

The present invention relates to an overhead door construction, and more particularly, to a novel counterbalance spring unit for an overhead door construction.

An important object of the present invention is to provide a novel counterbalance Spring unit for an overhead door which is constructed for facilitating installation of the door.

Still another important object of the present invention is to provide a novel counterbalance spring unit which may be pretensioned at the factory or at any other time prior to installation so as to reduce installation labor and time.

A further object of the present invention is to provide a novel counterbalance spring unit of simple and compact construction and adaptable for use with doors of widely varying weights.

Other objects and advantages of the present invention will become apparent from the following description and the accompanying drawings wherein:

FIG. 1 is a simplified sectional view showing an overhead door installation incorporating features of the present invention;

FIG. 2 is a perspective view showing a counterbalance spring unit incorporating features of the present invention; and

FIG. 3 is an enlarged fragmentary sectional view taken generally along line 33 in FIG. 1.

Referring now more specifically to the drawings wherein like parts are designated by the same numerals throughout the various figures, an overhead door installation incorporating features of the present invention is shown in FIG. 1. The installation comprises generally upstanding and horizontal track sections 12 and 14 connected by a curved track section 16 and a sectionalized door 18 of known construction carrying a plurality of rollers 20 adapted to ride in the track sections. A counterbalance spring unit 22 is mounted against a wall 24 above the door opening and is connected with the door as described in detail below. As will be understood, track sections essentially identical to those shown in FIG. 1 are disposed at an opposite side of the door opening and, if desired, a second counterbalance spring unit may be positioned at the opposite side of the door opening.

As shown in the drawings, the unit 22 comprises a bracket 26 preferably formed from sheet metal. The bracket 26 has a main body portion 28 and a laterally extending flange 30 adapted to abut against the wall 24 and having slots or apertures 32, 34 and 36 therein for accommodating screws or other fastening devices used for securing the flange against the wall 24.

In order to rigidify the main body portion 28 of the 3,413,680 Patented Dec. 3, 1968 bracket, elongated generally horizontally extending ribs 38, 40 and 42 are formed therein. In addition these ribs traverse the corner or junction between the main body portion 28 and the flange portion 30 for resisting bending or flexing of these portions relative to each other. A lower margin of the main body portion 28 terminates in a short laterally extending flange 44 which aids in strengthening the bracket.

The bracket 26 supports counterbalancing spring means as will be described below and, in addition, the bracket is adapted to be connected to and to support the door track. As shown in FIG. 2, apertures 46, 48 and 50 are provided along a lower marginal portion of the body 28 selectively for receiving a suitable bolt or fastener 52 as indicated in FIG. 1 for securing the track to the bracket. The position of the track with respect to the bracket is also shown in FIG. 3.

In order to counterbalance the weight of the door, the unit 22 is provided with a spiral spring 54 coiled from a thin strip of spring steel. The spring 54 has finger elements 56 or other suitable means at its inner end interengaging apertures or notches 58 in a tubular shaft 60. Similar fingers 62 or other suitable means are provided at an outer end of the spring for interengagement with a cylindrical wall 64 of a housing member having a radially extending wall 66. An opposite side of the housing member is closed by a radial wall 68 terminating in a short axially extending flange 70 telescopically associated with the cylindrical wall 64. A cable accommodating dru-rn 72 is associated with the housing and is welded or otherwise secured thereto. More specifically, the drum member 72 has an annular radially extending section 74 welded as at 76 to the housing Wall 66. The section 76 merges with a cylindrical cable accommodating section 78 which in turn merges with a radially extending end flange 80. The wall 66 of the spring housing projects radially beyond the cylindrical drum section 78 and, in effect, serves as one end flange of the cable drum.

The cable drum and spring housing are adapted to rotate as a unit relative to the tubular shaft 60 which in turn is mounted so as to be fixed against rotation. In order to facilitate relative rotation between the cable drum and the shaft 60, a sleeve bearing 82 is provided around the shaft 60 and is engaged by and supports an axially extending inner marginal portion 84 of the cable drum and an inner marginal portion 86 of the spring housing.

The tubular shaft 60 extends through and is supported by a sleeve 88. The sleeve 88 in turn extends through an aperture in the bracket body portion 28 and is supported by an annular axially extending flange 90 formed from the bracket body portion 28 and defining the aperture. The sleeve 88 is welded at at 92 or otherwise secured to the annular flange 90. A pin 94 is removably i'nsertable through aligned apertures 06 and 98 in the sleeve and selectively alignable apertures described more in detail below in the shaft 60 for retaining the shaft against rotation. The sleeve 88 is formed with an outer end flange 100 which provides a thrust bearing surface engageable with the inner axially extending flange portion 84 of the pulley or cable drum for maintaining the drum in the desired spaced relationship with respect to the bracket body portion 28. A pin 102 is inserted through an outer end portion of the shaft 60 for engagement with an annular axially extending flange portion 104 defining an inner margin of the casing or housing member 68 and thereby retaining the drum and housing assembly on the shaft. A similar pin 106 extends through an opposite end portion of the shaft for cooperative engagement with an inner end of the sleeve 88.

A cable 108 is wound in the drum 72 and has one end suitably fixed to the drum and an opposite end fixed by a fastener 110 to a lower portion of the door 18 as shown in FIG. 1. Thus the force provided by the spring '54 is applied through the cable 108 to the door for counterbalancing the weight of the door.

The unit is constructed so that the tension in the spring 54 may be adjusted for doors of different weights and also may be adjusted at the factory or at any other time prior to installation so as to facilitate the actual installation. In order to accomplish the adjustment prior to installation, a pin or other suitable fastener 112 is secured to and projects from the bracket body portion 28 for serving as a temporary anchor for a free end 114 of the cable 108. When the cable is anchored to the pin 112 and it is desired to adjust the tension of the spring 54, the above described pin 94 is withdrawn so that the shaft 60 is free to rotate. The shaft is provided with a plurality of series of axially spaced and diametrically oppositely disposed and aligned pairs of apertures 116 and 118. These apertures are adapted selectively to receive not only the pin 94 but also the pin 106 for permitting both rotary and axial adjustment of the shaft 60 relative to the sleeve 88. When the pin 94 has been removed as previously indicated, a suitable tool may be engaged with the exposed end portion of the shaft 60 and may, for example, be inserted through a selected pair of the apertures 116 and 118. Then with the aid of such a tool, the shaft 60 is rotated relative to the sleeve 88 and also relative to the cable drum and spring casing assembly so that the desired tension is imparted to the spring 54. When the adjustment has been completed, the pin 94 is reinserted for locking the shaft 60'.

While the tension of the spring 54 may be adjusted within limits imposed by the size and characteristics of the spring for accommodating doors of different weights, the unit is readily adaptable for accommodating doors having a weight greater than the capacity of the spring 54. This may be accomplished simply by inserting one or more additional springs 54a within the spring housing or casing and, of course, axially extending the cylindrical wall 64 to accommodate such additional springs. Preferably a separator disc 120 is disposed between the adjacent springs. It is to be understood, that for many installations, a single spring 54 will suflice while for other installations more than two springs may be provided. The aforementioned series of apertures 116 and 118 in the shaft 60 enables the shaft to be adjusted axially for accommodating the desired number of springs.

While a preferred embodiment of the present invention has been shown and described herein, it is obvious that many structural details may be changed without departing from the spirit and scope of the appended claims.

We claim:

1. A counterbalance spring unit for an overhead door assembly comprising a bracket adapted to be fixedly mounted adjacent a door opening and including a body portion, a substantially horizontal shaft fixed supported on said bracket body portion, a drum rotatably disposed on said shaft and having a diameter substantially greater than said shaft, a hollow housing member rotatably disposed on said shaft and connected to said drum for rotation in unison therewith, said housing member including a peripheral cylindrical wall of predetermined axial extent and opposite end walls substantially sealing said housing member, an elongated flexible element wound on said drum and having one end fixed thereto, means releasably connecting an opposite end of said element to said bracket, said opposite end of the element being connectable to a door when said unit is installed, first and second pretensioned spiral springs within said housing member and around said shaft and each spring having one end fixed to said shaft and an opposite end fixed to said housing member at a location spaced radially outwardly of said shaft for applying a predetermined force rotatably biasing said drum for pulling on said element and counterbalancing the weight of the door and a disc member disposed between and separating said springs.

2. A counterbalance spring unit for an overhead door assembly comprising a bracket adapted to be fixedly mounted adjacent a door opening and including a body portion, a substantially horizontal shaft supported by said bracket body portion and including a free end portion extending laterally from said body portion, means releasably locking said shaft against rotation, rotatable meanings having a diameter greater than said shaft and including a drum disposed on said shaft end portion and having a diameter greater than said shaft, an elongated flexible element wound on said drum and having one end fixed thereto and an opposite end connectable to a door when the unit is installed, said rotatable means including a housing member rotatably disposed on said shaft end portion and connected to said drum for rotation in unison therewith, said housing member including a peripheral cylindrical wall of predetermined axial extent and opposite end walls substantially sealing said housing member, and a spiral spring disposed within said hollow housing member and around said shaft end portion and having one end fixed to the shaft end portion and an opposite end fixed to said rotatable means at a location spaced radially outwardly of said shaft for applying a force rotatably biasing said drum for pulling on said element and counterbalancing the weight of the door, said shaft being manually rotatable relative to said bracket and said rotatable means upon release of said locking means for adjusting said spring.

3. A counterbalance spring unit for an overhead door assembly comprising a bracket adapted to be fixedly mounted adjacent a door opening and including a body portion, a substantially horizontal shaft rotatably supported by said body portion, means releasably locking said shaft against rotation relative to said body portion, rotatable means having a diameter greater than said shaft and including a drum rotatably disposed on said shaft and having a diameter greater than said shaft, an elongated flexible element wound on said drum and having one end fixed thereto, means releasably connecting an opposite end of said flexible element to said bracket, said opposite end of the flexible element being connectable to a door when said unit is installed, a pretensioned spiral spring around said shaft and having one end fixed to said shaft and an opposite end fixed to said rotatable means at a location spaced radially outwardly of said shaft for applying a predetermined force rotatably biasing said drum for pulling on said element and counterbalancing the weight of the door, said shaft being manually rotatable relative to said bracket and said rotatable means upon release of said locking means for adjusting the tension in said spring, said bracket being stamped from sheet metal and including a flange portion extending laterally from said body portion, said flange portion having aperture means therethrough adapting said bracket for receiving fasteners for mounting the bracket, said body portion including aperture means therethrough at a location beneath said shaft for receiving fasteners for securing a track member of the door assembly to the bracket, and said bracket including embossed ribs extending in said body and flange portion and traversing the junction between said portions.

4. A counterbalance spring unit for an overhead door assembly comprising a bracket adapted to be fixedly mounted adjacent a door opening and including a body portion, a substantially horizontal shaft rotatably supported by said body portion, means releasably locking said shaft against rotation relative to said body portion, rotatable means having a diameter greater than said shaft and including a drum rotatably disposed on said shaft and having a diameter greater than said shaft, an elongated flexible element wound on said drum and having one end fixed thereto, means releasably connecting an opposite end of said flexible element to said bracket,

said opposite end of said flexible element being connectable to a door when said unit is installed, a pretensioned spiral spring around said shaft and having one end fixed to said shaft and an opposite end fixed to said rotatable means at a location spaced radially outwardly of said shaft for applying a predetermined force rotatably biasing said drum for pullling on said element and counterbalancing the weight of the door, said shaft being manually rotatable relative to said bracket and said rotatable means upon release of said locking means for adjusting the tension in said spring, said bracket being formed from sheet metal and including a flange portion extending laterally from said body portion, said flange portion having aperture means therethrough adapting said bracket for receiving fasteners for mounting the bracket, said body portion including aperture means therethrough at a location beneath said shaft for receiving fasteners for securing a track member of the door assembly to the bracket, said bracket body portion having an aperture therethrough and including an annular flange defining said aperture, and said spring unit including a sleeve extending through said annular flange and welded to said body portion, said shaft being supported within said sleeve.

5. A counterbalance spring unit for an overhead door assembly comprising a bracket adapted to be fixedly mounted adjacent a door opening and including a body portion, a substantially horizontal shaft rotatably supported by said body portion, means releasably locking said shaft against rotation relative to said body portion, rotatable means having a diameter greater than said shaft and including a drum rotatably disposed on said shaft and having a diameter greater than said shaft, an elongated flexible element wound on said drum and having one end fixed thereto, means releasably connecting an opposite end of said flexible element to said bracket, said opposite end of said flexible element being connectable to a door when said unit is installed, a pretensioned spiral spring around said shaft and having one end fixed to said shaft and an opposite end fixed to said rotatable means at a location spaced radially outwardly of said shaft for applying a predetermined force rotatably biasing said drum for pulling on said element and counterbalancing the weight of the door, said shaft being manually rotatable relative to said bracket and said rotatable means upon release of said locking means for adjusting the tension in said spring, said bracket body portion being stamped from sheet metal and having an aperture therethrough, said unit including a sleeve member secured to said body portion and aligned with end extending from said aperture, said shaft being supported in said sleeve member, and anti-friction bearing means disposed between said shaft and said sleeve member and also disposed between said shaft and said rotatable means.

6. A counterbalance spring unit, as defined in claim 5, wherein said shaft includes an end portion projecting outwardly of said sleeve member, a plurality of aperture means extending transversely through said shaft end portion and also through a portion of the shaft within said sleeve member, additional aperture means extending through said sleeve member and selectively alignable with said first mentioned aperture means, and said releasable locking means comprising an element insertable into aligned aperature means in the sleeve member and shaft.

References Cited UNITED STATES PATENTS 1,186,720 6/1916 Westhoff 1678 2,257,484 9/1941 Rowe 16-198 2,262,914 11/1941 Bellmann et a1. 16198 2,314,015 3/1943 Parsons 16198 2,786,712 3/1957 Whiting 16-198 3,203,027 8/1965 Ohman 16-405 3,020,580 2/1962 Glenn 1661 FOREIGN PATENTS 147,103 9/1954 Sweden.

MARVIN A. CHAMPION, Primary Examiner. J. H. MCGLYNN, Assistant Examiner, 

